Instructors' speech and gestures are tightly integrated. However, little is known about the neural mechanisms by which different types of gestures affect learning. We conducted two experiments on the effects of gestures in video lectures that included an instructor and slides, with English vocabulary as the topic. In Experiment 1, we manipulated the instructor's gestures (beat gestures vs. pointing gestures vs. depictive gestures) on neural oscillations and learning performance. The electroencephalogram results showed that students had higher alpha power and higher beta power when the instructor used pointing gestures, suggesting lower sensorimotor involvement in processing. Pointing gestures produced lower learning performance than beat gestures and depictive gestures. In Experiment 2, we manipulated the instructor's pointing gestures and the richness of visual materials in video lectures. The results showed that the effectiveness of pointing gestures was moderated by the richness of the visual materials on the slide. Specifically, pointing gestures were more effective for complex versus simple learning materials. The findings suggest that electroencephalogram oscillations and learning performance vary with the type of gesture the instructor uses and the richness of visual materials in video lectures. This study has applied value for designing effective video lectures in many disciplines: (1) When a video lecture includes simple visual materials, a beat gesture and depictive gesture would be better; (2) when a video lecture includes complex visual materials, the instructor can produce pointing gestures to single out the learning content they are talking about.